1. Field of the Invention
This invention relates generally to a liquid flavoring valve arrangement for beverage dispensers, and more specifically, this invention relates to a valve arrangement utilizing a pressurized fluid to assist in closing a valve controlling discharge of a non-homogeneous liquid flavoring additive.
2. Description of the Prior Art
Beverage dispensers of the post-mix type utilize controlled discharges of a liquid flavoring or concentrate and a diluent, such as carbonated water, to form the drink to be dispensed. Solenoid valves are normally utilized to determine the amounts of concentrate and carbonated water that are introduced into a mixing chamber to produce the drink for dispensing. A conventional solenoid valve of this type utilizes a valve member biased toward engagement with a valve seat to close the valve. Actuation of the solenoid causes the valve member to move against the bias force to open the valve for a predetermined time.
The flavoring concentrate utilized is normally pressurized, such as by insertion of a pressurized gas or air at the top of a container in which it is stored, in order to force the concentrate through the valve at a known rate of flow. To assist in opening the valve when it is desired to discharge concentrate, it is possible to take advantage of the pressure on the concentrate. Thus, the valve member will frequently be located upon a larger plate or diaphragm upon which the pressurized concentrate will bear even when the valve is closed. When the solenoid valve is actuated to open the valve, the pressurized concentrate will assist the solenoid drive in producing immediate separation of the valve member from the valve seat. This immediate opening of the valve is important to proper operation, since the amount of concentrate discharged is a time function. Any tendency of the valve member to stick on the valve seat would result in a weak or watery drink. Therefore, the positive opening aspect of utilizing the pressurized concentrate to assist the solenoid actuator is of value.
While this system works quite adequately for a homogeneous concentrate (e.g., various soft drink concentrates added to carbonated water), systems utilizing non-homogeneous liquid concentrates, such as pulpy orange juice concentrate, present some difficulties. As a result of the tendency of such non-homogeneous liquids to block or clog a valve and its related conduits, the conduits and the related valve passages must have a greater cross sectional area. This means that the area of the diaphragm on which the valve member is located is also greater. This greater diaphragm area means that the biasing force has greater resistance to closing after de-energization of the solenoid, due to the concentrate pressure being applied to the greater surface area. This can result in a slow closure of the valve, with the subsequent dispensing of a drink that is too strong. Also, as a result of the larger opposing force during closing, the valve member may not be tightly engaged with the valve seat, so that concentrate may drip from the dispenser. Accordingly, it would be desirable to have a valve arrangement that produces positive and accurate closing, as well as positive and accurate opening.